In a charged particle beam device which irradiates a top of a sample with a charged particle as a probe, detects a secondary particle that is generated from the sample in accordance with the irradiation, or a charged particle that transmits through the sample, and obtains information with regard to a probe irradiation position from an intensity that is detected, there are presented a number of methods of obtaining specific information by selecting and detecting an energy of the charged particle.
Particularly, in a scanning electron microscope which obtains a two-dimensional image of a scanning region by two-dimensionally scanning an electron beam probe on a sample, there are presented a number of methods of discriminating to detect an energy of a signal electron that is generated from the sample.
As methods of using the fact that a signal electron draws a trajectory which differs by an energy, there are presented methods of Japanese Unexamined Patent Application Publication No. 2004-221089 (applicant: Leo Elektronenmikroskopie GmbH), and Japanese Unexamined Patent Application Publication No. 2002-110079 (applicant: Hitachi, Ltd.) which provide a sensing surface of a detector at a position at which only an electron of a specific energy is detected.
As methods of using a porous plate-like electrode (mesh electrode) which applies a negative voltage that supplies an electric field of shielding an electron of a specific energy or less at an interval between a sample and a sensing surface of a detector in a case where a trajectory of a signal electron is not changed by an energy, there are presented methods of Japanese Unexamined Patent Application Publication No. Hei 11(1999)-242941 (applicant: Hitachi, Ltd.), and WO Publication No. 99/46798 (applicant: Hitachi, Ltd.).
However, all of these methods are methods for carrying out high-pass detection, or low-pass detection. It has been impossible, for example, to carry out band-pass detection which emphasizes to detect only an electron of 10 keV through 20 keV in a signal electron which has an energy width of 1 keV through 30 keV when an irradiation energy of a primary electron beam is 30 keV.
As methods of carrying out band-pass detection, there are presented various kinds of methods of making multi-stage electric field barriers between plural mesh electrodes by applying voltages which differ in steps on the plural electrodes, and confining signal electrons energy band-passes of which are selected into respective potential barriers and detecting the signal electrons.
In Japanese Unexamined Patent Application Publication Hei 10(1998)-188883 (applicant: SHIMADZU CORPORATION), there is presented a method of detecting signal electrons band-passes of which are selected as current signals from respective mesh electrodes via floating amplifiers. In Japanese Unexamined Patent Application Publication No. 2006-114426 (applicant: Hitachi, Ltd.), there is presented a method of detecting a signal electron a band-pass of which is selected by an electron detector which is provided at an interval of mesh electrodes.
However, according to the methods, there pose problems by nonuniformity of an electric field by using the mesh electrode and a three-dimensional obstacle by the electrode, and effective detection cannot be expected. Furthermore, both of the methods need plural high voltage power sources for supplying the shielding electric fields, and it is necessary to contrive to provide a pertinent electrostatic withstand voltage. Therefore, a simple and convenient detector is not configured.
In Japanese Unexamined Patent Application Publication No. Hei 11(1999)-160438 (applicant: EL-MUL TECHNOLOGIES LTD.), there is presented a method of providing a thin film between a sensing surface of an MCP (microchannel plate) detector which is an electron detector and a sample. An object thereof resides in an effective detection of a high energy electron even in an MCP sensitivity of which is maximized at a low energy of about 300 eV. The high energy electron is subjected to an energy attenuation by the thin film and transmits through the thin film from a side of the sensing surface of the MCP. Or, the high energy electron is transformed into a subsidiary electron of an extremely low energy (<100 eV) on the side of the sensing surface of the MCP of the thin film. Thereby, the high energy electron can effectively be detected by MCP by detecting the extremely low energy electron after the transformation at high sensitivity.
According to the method, it is anticipated that band-pass detection can be carried out when a film thickness of the thin film is pertinently selected, and an electron of a desired energy is transformed to have an energy of precisely about 300 eV. However, the more hardly the energy is attenuated, the more the extremely low energy electron that is produced by the high energy electron on the surface of MCP is detected. As a result, only an effect as a high-pass filter is expected. It is anticipated that it is impossible to carry out band-pass detection which is achieved by not detecting the high energy electron.